Endre Bodnar

Long-term Performance of 555 Aortic Homografts in the Aortic Position

Long-term results with 555 aortic homografts used for isolated aortic valve replacement (AVR) between 1964 and 1986 were analyzed to assess valve performance and the time-related onset of valve-related events. The total follow-up was 2,931 patient-years. Twenty years after operation, overall survival was 51.6 +/- 8.1%, freedom from valve-related death was 67.1 +/- 8.9%, freedom from primary tissue failure was 12.4 +/- 4.8%, freedom from infective endocarditis was 82.7 +/- 4.3%, freedom from surgical technical failure was 88.1 +/- 2.3%, and freedom from all complications including valve-related death was 9.0 +/- 3.5%. The incidence of thromboembolism was 0.034% per patient-year (one potential event). Long-term results after homograft insertion for aortic stenosis were significantly better than those after insertion for aortic incompetence. It is concluded that the good quality of life and the median life expectancy, which extends more than 20 years after operation, make the homograft an excellent choice for AVR.

Long-term assessment of aortic valve replacement with autologous pulmonary valve

Two hundred two autologous pulmonary valves were transplanted into the aortic position between 1967 and 1982 at the National Heart Hospital in London. The indication for operation was congenital or acquired aortic valve disease, and the patients were followed for periods from 1 to 4 years. The patients were not anti-coagulated, but the entire series has been completely free from thromboembolism or bleeding. The actuarial prediction of freedom from valve-related deaths was 82 +/- 6% at the end of the fourteenth year after operation; deaths were due to reoperations for technical failure and to infective endocarditis. Event-free survival of the autologous pulmonary valve in the aortic position was 73 +/- 6% after 14 years at risk. Valve failure resulted mainly from technical problems encountered during the early years of surgical experience. There was no macroscopic or histological evidence of calcification in any of the failed valves. The right ventricular outflow was reconstructed with an aortic homograft in the majority of patients; 81 +/- 5% of these homografts demonstrated event-free performance over a 12-year follow-up period. It is concluded that the long-term performance of a pulmonary autograft inserted for aortic valve disease is superior to that of any other valve substitute and that the operation offers an almost ideal means of aortic valve replacement in appropriate patients.

Comparative method for actuarial analysis of cardiac valve replacements.

The use of survival analysis in cardiac surgical reports has been widely accepted in order to characterise and compare performances of different valve prostheses. However, the analyses that have been described elsewhere may be improved in several respects. The original method proposed for prosthetic valve evalation examined follow-up related to patients rather than the valves themselves and therefore neglected the possibility of factors other than the valve itself which could affect the fate of cardiac patients. Furthermore, there has not yet been any application of life table methods to compare two different sets of data, or to estimate the average time before an event occurs. The present work defines valve function and malfunction and separates patient survival from valve performance. We define statistical indices, namely the median remaining lifetime and the instantaneous decrement rate. Both indices can be useful; the former measures the average survival time and the latter focuses attention on the intensity of risk changes. Using established statistical theory we calculate the significance level of difference between two independent survival rates. We qualify the presentation of probabilities with a statement of the associated standard errors.

Assessment and comparison of the performance of cardiac valves.

A statistical method is presented to assess and compare cardiac valve performances. Patient survival and valve performances have been separated, and valve function and malfunction have been described in comprehensive and comparable terms. Formulas are proposed to calculate the significance of the difference between two survival probabilities as well as to calculate the instantaneous rate of events and the median remaining lifetime.

Homograft valves: is degeneration inevitable?

Since the first successful sub-coronary insertion (Ross 1962), the homograft aortic valve has been the favourite amongst many rypes of mechanicai or biological cardiac vaive repiacements ar the National Heart Hospital. Recent srudies on long rerm patient survivai afrer homograft insertion have reveaied excelient results (Bodnar er ai 1979), surpassed oniy by the autotranspianted puimonary valves. (Ross 1967; Ross et ai 1979). Ir is generally accepted that homograft vaives inserred into the aorric position have two major advantages (Ross 1962), they are non-thrombogenic, and (Bodnar et ai 1979) their haemodynamic performance is identicai to that of a normal aortic valve. However, two major disadvanrages are often reported as weii (Ross 1962): difficuities in the coilection, preparation and storage of these vaives, and (Bodnar et ai 1979) the rapid degenerarion which affects. the function of the homograft (Stinson et ai 1977; Anderson and Hancock 1976; Lefrak and Starr 1979). An analysis of the overali performance of the homograft vaive in the aortic posirion has show satisfactory long term resuits (Bodnar et ai 1979). The present work focuses attention on the degeneration of homograft valves in terms of incidence, onser and pattern.

Aortic valve replacement with homograft and autograft valves. Performance of 615 valves over 15 years.

SUBSTITUICAO DA VALVULA AORTICA COM HOMO E AUTOENXERTOS E analisado o comportamento, por um periodo de mais de 15 anos, de 6/5 homoenxertos e autoenxertos em posicao aortica. A incidencia de morte relacionada com o enxerto foi de 6,7%. A frequencia de tromboembolismo foi de 1 por 2314 doentes-anos. A insuficiencia valvular foi mais frequente no caso de homoenxertos « freeze-dried ». A endocardite infecciosa foi rara. Pensa-se que poucos homoenxertos continuarao a funcionar bem 20 anos apos a implantacao, mas 42% entrarao na 2a decada de existencia sem terem tido complicacoes. Os autoenxertos revelaram uma incidencia muito menor de degenerescencia. Muitas das complicacoes associadas com os homo e autoenxertos aparecem gradualmente uma reintervencao electiva